1. Field of the Invention
This invention relates to track-type vehicles and, more particularly, to an improved keying arrangement between a track shoe and a track link to reduce or eliminate shear stress on the bolts between said shoe and said link.
2. Description of the Prior Art
In track-type vehicles, there is a particular problem in retaining the track shoe of the track in proper position on the track link. The method most commonly in use is to bolt the track shoe to the track link, but often there are loads of such magnitude exerted against the track shoe that the shoe is moved relative to the link. This movement can cause the bolt to loosen or to break as a result of the shear loads placed on the bolt. The bolt may also bend causing high stress levels on the threads which also can lead to failure of the bolt and stripping of the threads in the link. Movement of the shoe relative to the link and bending of the bolts is especially a problem on the two-piece master link in the track because of the larger clearance holes that are required to provide for the stack-up of tolerances through the piece parts and the assembly.
U.S. Pat. No. 2,823,080 to E. C. Bauer, Jr. attempted to solve part of the problem by providing a pair of spaced apart retainers projecting downwardly from the grouser plate of the track shoe, which retainers engage with an enlarged tie bar extending between the respective track links. Although this construction helped to eliminate rotation of the track shoe relative to the links, it did not solve the problem of eliminating shear stresses on the bolts. In addition, the construction requires modifications of the grouser plate of the track shoe and of the link and requires that the two be used together to accomplish the desired result. It was also necessary to accurately position the abutments on the grouser plate relative to the openings for the bolts to the links since, in order for the restraint on rotation provided between the abutments and the tie bar to be effective, they must fit tightly together to eliminate looseness or play between the track shoe and the link.
Another structure directed to the problem provided for slots formed in the top surfaces of the adjacent links and struck down portions or cast portions formed on the under surface of the grouser plate of the track shoe, which struck down portions were intended to nest in and align with the slots in the links so as to prevent the track shoes from rotating or shifting relative to the links. This system had the same shortcomings as the Bauer patent in that it was necessary to provide very accurate matching between the struck down portions and the walls of the slots so as to eliminate play between the track shoe and the links. The system also required modifications particularly of the track shoe, i.e. by providing the struck down portions, which made the track shoe usable only with links that have mating slots.